Synthesis And Structural Characterization Of New Rhodium Complexes And Their Catalytic Performance In Coordination Polymerization Of Monosubstituted Alkynes

Late transition metal rhodium complexes,which are stable for water,oxygen and polar groups,exhibits high efficiency and selectivity in the coordination polymerization of various single substituted alkynes under mild and green reaction conditions,producing a series of functional polyynes materials with unique structures and properties.However,the auxiliary ligands for rhodium complexes are very limited for now.Meanwhile,rhodium complexes which could accelerate the “on water” polymerization of alkynes,or that possess bimetal synergy effect or chiral or AIE property are also rare.Therefore,developing new rhodium complexes as highly efficient and selective catalysts for the coordination of single substituted alkynes still remains challenging and is of great scientific significance.This paper mainly concentrated on the synthesis of rhodium complexes with novel structures by designing new supporting ligands,and then explored their application to the coordination polymerization of single substituted alkynes exhibiting high efficiency and selectivity.Detailed investigation are shown below:(1)Considering that the types of traditional diene ligands are limited,we developed high-efficiency and high-selectivity new rhodium complexes bearing dibenzo[a,e][8]annulene ligand,accelerating the “on water” aqueous polymerization of mono-substitute alkynes.We synthesized and characterized four new mononuclear rhodium catalysts including a neutral complex(dbcot)Rh Ph3 Cl and three cationic complexes [(dbcot)Rh LL`]+OTf-.Such complexes could catalyze phenylacetylene polymerization with high efficiency and stereoselectivity in organic solvents without any cocatalyst,obtaining high cis-polyphenylacetylene(cis-transoid 99%).Moreover,we achieved accelerated “on water” polymerization of phenyaceltylene and its derivatives for the first time.In aqueous polymerization,the catalysts still exhibited high catalytic activity when recycled for three times.(2)In consideration of the low catalytic activity of traditional complexes,we developed binuclear rhodium complexes exhibiting bimetallic synergy effect and enhanced catalytic activity in alkyne polymerization.We synthesized three different bridging bi-functional group salicylaldiminato ligands including phenyl bridging,adjacent diphenyl bridging and naphthyl bridging ligands.Then we prepared and characterized six new binuclear rhodium complexes and two mononuclear rhodium complex.When THF used as solvent,the phenyl bridging binuclear rhodium complex exhibited noticeable bimetal synergy effect in the coordination polymerization of phenylacetylene.The catalytic activity could reach up to 205 kg/mol Rhh which was 30 times as much as that of corresponding mononuclear rhodium complex.Similar results were also obtained when toluene and CH2Cl2 used as solvents.The bimetal synergy effect probably resulted from the weak electron-donating ability of phenyl bridging ligand which contributed to more electropositivity of the rhodium metal center and thus accelerated the coordination insertion rate of alkyne monomers.(3)We developed a series of chiral rhodium complexes in order to achieve achieve helix-sense-selectives polymerization.We firstly synthesized five chiral amino ligands indcluding benzyl or ferrocene benzyl substituent group,and then prepared and characterized corresponding five new chiral rhodium complexes.When used in the polymerization of phenylacetylene derivatives without any cocatalyst and chiral inductive agent,three asymmetric rhodium complexes could achieve helix-sense-selective polymerization.Meanwhile,we found that the different substituent groups of ligands contributed to different structured polyynes.(4)As for the fact that rhodium complexes and polyynes possessing AIE property are limited,we synthesized nine alkyne monomers which processed optical activity and AIE property.We obtained nine single spiral structured polyynes with AIE property catalyzed by traditional rhodium complexes.More important,we firstly succeeded in adjusting the helix structure of polyynes via modifying the number of substituent groups on the same atom of the monomer side chain.